The proposed study is a continuation of the x-ray crystallographic study of the enzyme L-asparaginase from proteus vulgaris. L-asparaginase is an anti-tumor agent clinically effective against human acute lymphoblastic leukemia. The goal of the research is to establish a 3 Angstrom resolution three-dimensional structure of this enzyme by means of the single crystal x-ray crystallographic techniques. We hope that the knowledge of the detailed three-dimensional structure of the enzyme will significantly aid in increasing our understanding of the mechanism of various physiological effects of the drug and will possibly point ways to improve the drug by means of chemical modifications.